-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 @stake, Inc. www.atstake.com Security Advisory Advisory Name: Sun ONE (iPlanet) Application Server Connector Module Overflow Release Date: 03/13/2003 Application: SunONE (iPlanet) Application Server 6.x Platform: Microsoft Windows (NT 4.0/2000) Severity: Remote arbitrary code execution Author: Kevin Dunn (kdunn@atstake.com) Chris Eng (ceng@atstake.com) Vendor Status: Vendor has patch for 6.5, no fix for 6.0 CVE Canditate: CAN-2002-0387 Reference: www.atstake.com/research/advisories/2003/a031303-1.txt Summary: A stack buffer overflow exists in the Connector Module that ships with the Sun ONE Application Server. The module is an NSAPI plugin that integrates the Sun ONE Web Server (formerly iPlanet Enterprise Server) with the Application Server. Incoming HTTP request URLs are handled by the module and an unbounded string operation causes the overflow. This is a classic stack buffer overflow and a remote attacker can gain control of the running web server. Detailed Description: The gxnsapi6.dll module that ships with the Sun ONE application server uses a static buffer in the handling of the incoming request URI. An overly long request URI in the form of /[AppServerPrefix]/[long buffer] will cause the overflow. The condition is exploitable as the saved EIP register is overwritten. Vendor Response: The vendor was initially contacted via email on 5/22/2002. Vendor has a patch available for Sun One Application Server 6.5. Download SP1 at: http://wwws.sun.com/software/download/products/3e3afb89.html Vendor has no patch available for version 6.0. Queries to the vendor as to the best solution for 6.0 customers were not answered. Recommendation: If you are using version 6.5 you should and you are able to patch your server you should apply SP1. We offer the following recommendations for those using version 6.0 or are unable to apply SP1 to 6.5. There are a number of things that can be done to partially or wholly mitigate the risk posed by this vulnerability. The following are some examples. The reader is encouraged to understand their environment and business needs and base their solution around those. * Use or write an NSAPI module similar to the sample provided to inspect the length of HTTP request URIs. The module could be run as the very first NameTrans directive in the default object so that it will apply to all incoming requests. The sample allows a maximum length for the URI to be specified in the obj.conf file, will log an error if it is exceeded, and will send a "440 Possible Attack Detected" response to the client. * Terminate the SSL session on a device before the Sun ONE web server and install an IDS sensor to monitor the clear-text traffic. Write a filter to detect abnormally long HTTP request URIs. * Terminate the SSL session on a reverse-proxy that performs data validation on all HTTP request headers. If a specified length is exceeded or a pattern matches, log, alert, and send a warning down to the client. ============================= NSAPI Data Validation Module: ============================= Usage: In [server-root]/[server-instance]/config/obj.conf: ... Init fn="load-modules" shlib="[path to libs]/long.so" funcs="bounds_check" # Make sure this function is the first to be called NameTrans fn=bounds_check maxlength=500 ... ----- BEGIN ----- #include "nsapi.h" static int max_req_len = 0; NSAPI_PUBLIC int bounds_check(pblock *pb, Session *sn, Request *rq) { char *temp; max_req_len = atoi(pblock_findval("maxlength", pb)); temp = pblock_findval("uri", rq->reqpb); if (temp != NULL) { if (strlen(temp) > max_req_len) { log_error(LOG_SECURITY, "bounds_check", sn, rq, "Overly long URI header (%d bytes)... aborting.", strlen(temp)); protocol_status(sn, rq, 440, "Potential Attack Detected"); return REQ_ABORTED; } } return REQ_NOACTION; } ----- END ----- Common Vulnerabilities and Exposures (CVE) Information: The Common Vulnerabilities and Exposures (CVE) project has assigned the following names to these issues. These are candidates for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. CAN-2002-0387 @stake Vulnerability Reporting Policy: http://www.atstake.com/research/policy/ @stake Advisory Archive: http://www.atstake.com/research/advisories/ PGP Key: http://www.atstake.com/research/pgp_key.asc @stake is currently seeking application security experts to fill several consulting positions. Applicants should have strong application development skills and be able to perform application security design reviews, code reviews, and application penetration testing. Please send resumes to jobs@atstake.com. Copyright 2003 @stake, Inc. All rights reserved. -----BEGIN PGP SIGNATURE----- Version: PGP 8.0 iQA/AwUBPnCz4Ue9kNIfAm4yEQJkOACfXdDVFUFCGSrJqw3FGOrDXYkPQLkAoKEC rPaKbHt36eSVdU/4HP8XIPQf =WbKy -----END PGP SIGNATURE-----